files.java

一个自然语言处理的Java开源工具包。LingPipe目前已有很丰富的功能

        try {
            fileOut = new FileOutputStream(file);
            bufOut = new BufferedOutputStream(fileOut);
            objOut = new ObjectOutputStream(bufOut);
            objOut.writeObject(object);
        } finally {
            Streams.closeOutputStream(objOut);
            Streams.closeOutputStream(bufOut);
            Streams.closeOutputStream(fileOut);
        }
    }

    /**
     * Returns the name of a file before the final period separator.
     *
     * @param name Name of file.
     * @return File name's prefix.
     */
    public static String prefix(String name) {
        int lastDotIndex = name.lastIndexOf('.');
        if (lastDotIndex < 0) return name;
        return name.substring(0,lastDotIndex);
    }


    /**
     * Returns the name of a file after the final period separator.
     *
     * @param name Name of file.
     * @return File name's suffix.
     */
    public static String suffix(String name) {
        int lastDotIndex = name.lastIndexOf('.');
        if (lastDotIndex < 0) return "";
        if (lastDotIndex >= name.length()) return "";
        return name.substring(lastDotIndex+1);
    }


    /**
     * Returns prefix of the file's name.
     *
     * @param file File whose name's prefix is returned.
     * @return Prefix of file.
     */
    public static String baseName(File file) {
        return prefix(file.getName());
    }

    /**
     * Removes the specified file and if it is a directory, all
     * contained files.  Returns number of files removed, including
     * specified one.
     *
     * @param file File or directory to remove.
     * @return Number of files and directories removed.
     */
    public static int removeRecursive(File file) {
        if (file == null) return 0; // nothing to remove
        int descCount = removeDescendants(file);
        file.delete();
        return descCount + 1;
    }

    /**
     * Remove the descendants of the specified directory, but not the
     * directory itself.  Returns number of files removed.
     *
     * @param file File whose descendants are removed.
     * @return Number of files or directories removed.
     */
    public static int removeDescendants(File file) {
        if (!file.isDirectory()) return 0;
        int count = 0;
        File[] files = file.listFiles();
        for (int i = 0; i < files.length; ++i)
            count += removeRecursive(files[i]);
        return count;
    }

    /**
     * Creates a clean directory with the specified name
     * as a subdirectory of the specified directory.
     *
     * @param directory Parent directory of directory to create.
     * @param name Name of directory to create.
     * @return Directory with specified name that is daughter of
     * specified parent directory.
     */
    public static File makeCleanDir(File directory, String name) {
        return makeCleanDir(new File(directory,name));
    }

    /**
     * Creates a directory in the specified file that has no
     * subdirectories.  If the specified file exists as a file, it
     * is removed first.  If the specified file is a directory with
     * files or subdireictories, they are removed.
     *
     * @param file File to create as a clean directory.
     * @return Directory with specified name that is daughter of
     * specified parent directory.
     */
    public static File makeCleanDir(File file) {
        if (file.exists() & !file.isDirectory()) file.delete();
        if (!file.isDirectory()) file.mkdir();
        removeDescendants(file);
        return file;
    }

    /**
     * Returns a new file with the specified name that is a daughter
     * of the temporary directory {@link #TEMP_DIRECTORY}.  The file
     * will be deleted automicatically when the virtual machine exits.
     *
     * @param fileName Name of file to create.
     * @return Temporary file with specified name.
     */
    public static File createTempFile(String fileName) {
        File tempFile = new File(TEMP_DIRECTORY,fileName);
        tempFile.deleteOnExit();
        return tempFile;
    }

    /**
     * Converts a file to the string representation of its URL,
     * consisting of the URL prefix and a canonical path name.
     *
     * @param file File to convert to string URL.
     * @return The string URL corresponding to the specified file.
     * @throws IOException If there is an exception retrieving the
     * file's canonical path name.
     */
    public static String fileToURLName(File file) throws IOException {
        return FILE_URL_PREFIX + file.getCanonicalPath();
    }

    /**
     * Returns the lines of a file as an array of strings.  The
     * newline characters are removed.
     *
     * @param file Name of file from which to read lines.
     * @param charset Character set to use to read lines.
     * @return Array of lines read from file.
     * @throws IOException If there is an I/O exception opening,
     * closing, or reading from the file.
     */
    public static String[] readLinesFromFile(File file, String charset)
        throws IOException {

        FileInputStream in = null;
        InputStreamReader streamReader = null;
        BufferedReader reader = null;

        try {
            in = new FileInputStream(file);
            streamReader = new InputStreamReader(in,charset);
            reader = new BufferedReader(streamReader);
            ArrayList list = new ArrayList();
            String line;
            while ((line= reader.readLine()) != null) {
                list.add(line);
            }
            return Collections.toStringArray(list);
        } finally {
            Streams.closeInputStream(in);
            Streams.closeReader(streamReader);
            Streams.closeReader(reader);
        }
    }

    /**
     * Serializes the specifies object and returns its deserialized
     * version.  This operates in memory by writing to a byte-array
     * backed object output stream and reading from a byte-array
     * backed object input stream.
     *
     * @param in Object to serialize and then deserialize.
     * @return Deserialized version of serialized version of specified
     * object.
     * @throws IOException If there is an I/O error while reading or
     * writing.
     * @throws ClassNotFoundException If the class for the object
     * being restored cannot be found.
     *
     */
    public static Object serializeDeserialize(Serializable in)
        throws ClassNotFoundException, IOException {
        ByteArrayOutputStream bytesOut = new ByteArrayOutputStream();
        ObjectOutputStream objOut = new ObjectOutputStream(bytesOut);
        objOut.writeObject(in);
        byte[] bytes = bytesOut.toByteArray();
        ByteArrayInputStream bytesIn = new ByteArrayInputStream(bytes);
        ObjectInputStream objIn = new ObjectInputStream(bytesIn);
        return objIn.readObject();
    }

    /**
     * Copies the contents of one file into another.  Even if there
     * is an exception, both file handles will be closed on exit.
     *
     * @param from File from which to copy.
     * @param to File to which to copy.
     * @throws IOException If there is a read or write error.
     */
    public static void copyFile(File from, File to) throws IOException {
        FileInputStream in = null;
        FileOutputStream out = null;
        try {
            in = new FileInputStream(from);
            out = new FileOutputStream(to);
            byte[] bytes = new byte[1024*4];
            int len = 0;
            while ((len = in.read(bytes)) >= 0)
                out.write(bytes,0,len);
        } finally {
            Streams.closeInputStream(in);
            Streams.closeOutputStream(out);
        }
    }

    /**
     * Prefix for file names to convert them into URLs.
     */
    private static String FILE_URL_PREFIX = "file:///";

    /**
     * Name of the property for the system temporary directory.
     */
    private static final String TEMP_DIRECTORY_SYS_PROPERTY = "java.io.tmpdir";

    /**
     * The temporary directory.
     */
    public static final File TEMP_DIRECTORY
        = new File(System.getProperty(TEMP_DIRECTORY_SYS_PROPERTY));


    /**
     * A file filter that accepts files that are directories
     * that are not named "CVS", ignoring case.
     */
    public static final FileFilter NON_CVS_DIRECTORY_FILE_FILTER
        = new FileFilter() {
                public boolean accept(File file) {
                    return file.isDirectory()
                        && !file.getName().equalsIgnoreCase("CVS");
                }
            };

    /**
     * A file filter that accepts all normal files, as
     * specified by {@link File#isFile()}.
     */
    public static final FileFilter FILES_ONLY_FILE_FILTER
        = new FileFilter() {
                public boolean accept(File file) {
                    return file.isFile();
                }
            };


}